Digital Marketing

What Is Open Rate?

Definition

The percentage of email recipients who open a given email, used as a key metric for email marketing campaign performance.

Why It Matters

Open rate indicates whether your subject lines are compelling enough to earn attention in a crowded inbox. A declining open rate is an early warning sign of list fatigue, deliverability problems, or a growing mismatch between subscriber expectations and your actual content.

How It Works

Open rate is tracked via a tiny pixel image embedded in the email — when the image loads, the open is recorded. Since Apple's Mail Privacy Protection (MPP) launched in 2021, this metric has become less reliable for iOS users, as Apple's system pre-loads images regardless of whether the email was actually opened. Click rate is now considered a more reliable engagement signal.

Real-World Example

A marketing agency notices their open rate drops from 28% to 18% over three months. Investigation reveals a large proportion of inactive subscribers dragging down the average. After removing contacts who have not engaged in six months, average open rates recover to 31%.

Quick Facts

Average open rates vary significantly by industry — B2B averages ~21%, e-commerce ~15%
Personalising the subject line with the recipient's first name can increase open rate by up to 26%
Tuesday and Thursday mornings typically achieve the highest open rates across most industries
Apple MPP (2021) inflates open rate figures for iOS 15+ users — use click rate as a supplementary metric